Process for degumming raw silk in presence of vat-dyed silk



UNITED STATES PATENT OFFICE.

HEINRICH BERNHARD AND OSKAR JAECK, 0F BASEL, SWITZERLAND, ASSIGNORS TO SOCIETY OF CHEMICAL INDUSTRY IN BASLE, OF BASEL, SWITZERLAND.

PROCESS FOR DEGUMMING RAW SILK IN PRESENCE OF VAT-DYED SILK.

No Drawing.

To (17] 2 37mm 1'? may concern.

Be it known that we. Hnmniorr BERN- imnn and ()snzxn JAECK, both citizens of the Swiss Republic, and residen s of Basel, Switzerland, have invented a new and useful Process for Degumming Raw Silk in Presence of Vat-Dyed Silk, of which the following is a full, clear and exact specification.

\Vhen, according to the usual methods, one essays to deguni or ungum raw silk with a hot soap solution in presence of silk dyed with vat-dyestuffs. one observes often that the dyestuff of the vat-dyed silk is partly reduced and runs or is disgorged more or less in the silk subjected to the ungumrning;

If. searching to obviate this drawback, an oxidizing agent, hydrogen peroxide or an alkali-metal perborate, be added to the ungunirning hath, no appreciable improvement is observed. In the course of our investigations, we have found, that this inconvenience can be avoided if a small quantity of an alkali metal persulfate is added to the soapy degumming bath. This addition prevents the reduction of such vat dyestuffs which are sensitive to the action of the degumming bath and therefore such dyestuffs can thus be employed for fancy Coloured woven fabrics.

Specification of Letters Patent.

Application filed September 13, 1921.

Patented Mar. 14, 1922.

Serial No. 500,375.

Ema Iraqis.

1 part of silk dyed with eiba violet B and 10 parts of aw silkare boiled together, for 2 hours in a deguniming bath containing 15 of soap of Marseille and 2 gr. of potassium persulfate per liter. No reduction of the dyest-uif is observed and the silk, which has been ungummed, remains white. An analogous result is obtained ith other vat-dyestuffs, as for. instance ciba-brown B, ciba-grey C, helindon-pink AN, helindon-scarlet R.

What we claim is:

The herein described process for degumining raw silk in presence of vat-dyed silk wherein an alkali-metal persulfate is added to, the ungumming. bath, thus preventing the vat-dyestuff from being reduced and running onto the undyed silk during the process of ungumming.

In witness whereof we have hereunto signed our names this 27th day of August, 192-1. in the presence of two subscribing witnesses.

HEINRICH BER-NHARD. ()SKAR JAECK.

lVitnesses Fiusnsn lxunz, AMAND Rr'rrnn. 

